fixes for browser.tests api test cases

Hi Hackers,

Please find here attached patch for the following test cases,(in package
pgadmin.browser.tests) which were failing.

- test_change_password
- test_gravatar_image_display
- test_login
- test_logout
- test_reset_password
- test_version_in_range

following fixes are provided

- Overridden base class setUp function, as if there is any issue in the
base class setup code, it fails the test case uselessly.
- Changed 'active' parameter value to boolean from integer in following
api '/user_management/user/'

in the test case ,as the relevant post function accepts value in
boolean. Currently due to this the test case was failing.

Please review the patch and commit.

Note: I have verified it on Python2.7 & Python3.6.
--

Thanks,

Usman Muzaffar
QA Team
EnterpriseDB Corporation